Offset printing ink is quite thick; frequently, therefore, doctor blade arrangements which permit application of an ink film to a duct roller are so placed that the doctor blade bears against the lower portion of a duct roller, and is confined by the duct roller, the doctor blade, and additional structural elements of the inking system, for example a cross rail and side walls to define, in combination with the duct roller, an ink trough. Inking systems of this type are known in the literature, see, for example, U.S. Pat. No. 3,611,928, to which German Pat. No. 1,943,130 corresponds and German Pat. No. 1,053,530. The German Pat. No. 1,053,530 discloses an arrangement in combination with an ink trough in which a doctor blade can be placed more or less against an ink duct roller by a rail extending parallel to the ink duct roller. The thickness of the ink film can thus be changed, while retaining the setting in individual zones as controlled by the adjustment screws. To clean the ink trough, for example in order to remove ink to replace it with ink of a different color, or generally for cleaning and maintenance, it is necessary to tilt the entire ink trough. It is known that fixed ink troughs are difficult to clean since the ink has to be removed with scrapers or with blade-like tools. Tipping the entire trough arrangement facilitates emptying the ink trough, but requires substantial force since the ink trough and the associated apparatus are heavy. Entirely apart from the handling difficulty due to the weight, spilling or contacting inkcoated parts can hardly be avoided, so that the general danger of soiling makes the task of cleaning disagreeable and difficult. Additionally, removal of ink by scooping out ink from a trough, even with a blade-like tool, is very time-consuming.